President Obama’s Twitter account, which is run by his "Organizing for Action" staff, follows 636,000 accounts. Many of them you might expect: Michelle Obama, Joe Biden, John Kerry. Even Mariah Carey and Snoop Dogg don't really raise an eyebrow. But several accounts on the presidential follow list fit a different theme: Asa Akira, a porn star who has 653,000 followers and, in her Twitter bio, states "I have an award-winning asshole." Joanna Angel (390,000 followers), who describes herself as a "multiple award winning punk porno princess;" Penthouse Pet Of The Year Nikki Benz (808,000 followers); and Ashley Steel (138,000 followers), who writes that she is a "Porn Star, Doggy mama, Happiness Junkie, XXX Model, Buddhist, & Total nerd."

So why is the official Twitter account for the president of the United States publicly following adult movie stars? Of course, American porn stars are just as American (and just as worthy of the President's ear) as anyone else, but this interaction is nonetheless an unusual move for an elected official's campaign-managed social media account.

Neither the Organizing for Action campaign nor the White House immediately responded to a request for comment. A spokesperson for Joe Rospars, Obama's principal digital strategist for both presidential campaigns, said that he was not available to comment.

The most likely culprit is a piece of Twitter etiquette known as the "follow back." Some consider it polite to follow your followers, and until recently, only Twitter accounts that followed each other could communicate through direct messages, which added a practical component to the tradition. Twitter once had an "auto-follow" feature that handled this process on behalf of users by automatically following any new followers. Twitter removed that auto-follow feature from its own site in 2009, but the capability stuck around in its API until 2013, allowing many third-party tools to set accounts to "auto-follow" regardless.

Even if a social media agency or volunteer had controlled for variables like number of followers, which can indicate the legitimacy of an account, it wouldn’t necessarily have filtered accounts from, say, popular porn stars.

Twitter follow lists are technically public, but within the Twitter interface, followers can only be viewed by scrolling through every account: quite a task when you are following several hundred thousand people. "I would assume [someone in Obama’s position] doesn’t even know that they’re following those accounts," says Stephanie Abrams Cartin, the founder and CEO of a New York City-based social media PR agency called Socialfly. Though social media audience management tools that make it easy to pinpoint an account’s following habits—including SocialRank, Little Bird, and Crowdfire—weren’t around when Twitter was getting started, they can reveal mistakes made in those early days of auto-follow that might have otherwise been forgotten. "There are smart things to automate like reporting and analytics—but follows, likes, tweets —smart social media managers and brands stay away from that; just too much that can go wrong,"says SocialRank CEO and Founder Alex Taub.

The increased visibility of follow lists is a problem for brands and political candidates who carelessly followed accounts with the hope of raising follower accounts or appearing engaged, because who you follow indicates to some extent where your interests lie. "If you’re following people who aren’t relevant to who you are a person or who your brand is, then it could be cause for concern," Abrams Cartin says.

The current presidential candidates seemed to have been more intentional about their follow lists, if for no other reason than that Twitter had blocked auto-following before the start of their 2016 campaigns. Nikki Benz, Penthouse's 2011 "Pet Of The Year," has followed Bernie Sanders, Hillary Clinton, and Donald Trump. None of them have followed back.